The present invention relates to generating a three dimensional representation of an object that may vary in position, orientation, and shape. More specifically, but without limitation thereto, the present invention relates to illuminating a substance with excitation energy to generate a visible representation of a three dimensional object within a spatial volume.
3-D display technologies such as holography, stereoscopic displays, and advanced 3-D graphics engines generally render three dimensional (3-D) images on a two dimensional (2-D) display by mapping the coordinates of the 3-D images into a 2-D perspective. However, these technologies lack the physiological depth cues needed for true 3-D display imaging, such as motion parallax, accommodation, convergence, and binocular disparity. A 3-D volumetric display provides the physiological depth cues needed for such applications as air traffic control, submarine undersea navigation, automotive design, architecture, and medical imaging.
One method for displaying a true three-dimensional image is to illuminate a series of points on a two-dimensional surface as it moves through a display volume. However, these volumetric displays suffer the disadvantages of mechanical constraints on the voxel refresh rate, because a voxel may only be refreshed when the display surface is in the correct position within the display volume. A voxel is defined as a graphic unit of information representative of a point in a three dimensional image space, analogous to a pixel as a graphic unit of information representative of a point in a two dimensional image space. This type of display also suffers from the disadvantages of instability in the moving two dimensional surface that may cause the image to jitter, added weight and mechanical complexity that may make shipboard and aircraft applications impractical, and the display surface motion itself that may distract attention from the image being displayed.
Another approach to a 3-D display is described in U.S. Pat. No. 5,684,621 issued on Nov. 4, 1997 to Elizabeth Downing and incorporated herein by reference thereto. This display suffers from the disadvantages associated with voxels that require expensive rare earth crystalline materials and the impracticality of scaling to large sizes.
A need therefore exists for a three dimensional volumetric display that does not require a two dimensional surface within the display volume and which may readily be scaled in size.
The present invention is directed to overcoming the problems described above, and may provide further related advantages. No embodiment of the present invention described herein shall preclude other embodiments or advantages that may exist or become obvious to those skilled in the art.
A three dimensional display of the present invention provides a true 3-D display of an image defined by luminous voxels within a virtually transparent display volume. The voxels may be generated by illuminating a fluorescent gas with multiple beams of excitation energy that cause the gas to emit light at voxels where the energy beams intersect. The voxels may be refreshed in a manner to create either fixed or animated images within the display volume.
An advantage of the three dimensional display of the present invention is that a true 3-D image may be generated within a virtually transparent volume without the refractive distortions of solid media.
Another advantage is that the weight and cost of the display materials is substantially reduced over that of solid state displays that require a glass doped with rare earth ions.
Still another advantage is that highly visible displays may be generated with low power lasers.
Yet another advantage is that the three dimensional display of the present invention may readily be scaled in size.
The features and advantages summarized above in addition to other aspects of the present invention will become more apparent from the description, presented in conjunction with the following drawings.